finlabsindia/wp-content/plugins/jetpack/modules/theme-tools/content-options/featured-images-fallback.php

<?php
/**
 * Get one image from a specified post in the following order:
 * Featured Image then first image from the_content HTML
 * and filter the post_thumbnail_html
 *
 * @param string       $html              The HTML for the image markup.
 * @param int          $post_id           The post ID to check.
 * @param int          $post_thumbnail_id The ID of the featured image.
 * @param string       $size              The image size to return, defaults to 'post-thumbnail'.
 * @param string|array $attr              Optional. Query string or array of attributes.
 *
 * @return string      $html              Thumbnail image with markup.
 */
function jetpack_featured_images_fallback_get_image( $html, $post_id, $post_thumbnail_id, $size, $attr ) {
	$opts = jetpack_featured_images_get_settings();

	if ( ! empty( $html ) || (bool) 1 !== (bool) $opts['fallback-option'] ) {
		return trim( $html );
	}

	if ( jetpack_featured_images_should_load() ) {
		if (
			( true === $opts['archive'] && ( is_home() || is_archive() || is_search() ) && ! $opts['archive-option'] )
			|| ( true === $opts['post'] && is_single() && ! $opts['post-option'] )
			|| ! $opts['fallback-option']
		) {
			return trim( $html );
		}
	}

	if ( class_exists( 'Jetpack_PostImages' ) ) {
		global $_wp_additional_image_sizes;

		$args = array(
			'from_thumbnail'  => false,
			'from_slideshow'  => true,
			'from_gallery'    => true,
			'from_attachment' => false,
		);

		$image = Jetpack_PostImages::get_image( $post_id, $args );

		if ( ! empty( $image ) ) {
			$image['width']  = '';
			$image['height'] = '';
			$image['crop']   = '';

			if ( array_key_exists( $size, $_wp_additional_image_sizes ) ) {
				$image['width']  = $_wp_additional_image_sizes[ $size ]['width'];
				$image['height'] = $_wp_additional_image_sizes[ $size ]['height'];
				$image['crop']   = $_wp_additional_image_sizes[ $size ]['crop'];
			}

			$image_src = Jetpack_PostImages::fit_image_url( $image['src'], $image['width'], $image['height'] );

			// Use the theme's crop setting rather than forcing to true
			$image_src = add_query_arg( 'crop', $image['crop'], $image_src );

			$html      = '<img src="' . esc_url( $image_src ) . '" title="' . esc_attr( strip_tags( get_the_title() ) ) . '" class="attachment-' . esc_attr( $size ) . ' wp-post-image" />';

			return trim( $html );
		}
	}

	return trim( $html );
}
add_filter( 'post_thumbnail_html', 'jetpack_featured_images_fallback_get_image', 10, 5 );

/**
 * Get URL of one image from a specified post in the following order:
 * Featured Image then first image from the_content HTML
 *
 * @param int          $post_id           The post ID to check.
 * @param int          $post_thumbnail_id The ID of the featured image.
 * @param string       $size              The image size to return, defaults to 'post-thumbnail'.
 *
 * @return string|null $image_src         The URL of the thumbnail image.
 */
function jetpack_featured_images_fallback_get_image_src( $post_id, $post_thumbnail_id, $size ) {
	$image_src = wp_get_attachment_image_src( $post_thumbnail_id, $size );
	$image_src = ( ! empty( $image_src[0] ) ) ? $image_src[0] : null;
	$opts      = jetpack_featured_images_get_settings();

	if ( ! empty( $image_src ) || (bool) 1 !== (bool) $opts['fallback-option'] ) {
		return esc_url( $image_src );
	}

	if ( jetpack_featured_images_should_load() ) {
		if ( ( true === $opts['archive'] && ( is_home() || is_archive() || is_search() ) && ! $opts['archive-option'] )
			|| ( true === $opts['post'] && is_single() && ! $opts['post-option'] ) ) {
				return esc_url( $image_src );
		}
	}

	if ( class_exists( 'Jetpack_PostImages' ) ) {
		global $_wp_additional_image_sizes;

		$args = array(
			'from_thumbnail'  => false,
			'from_slideshow'  => true,
			'from_gallery'    => true,
			'from_attachment' => false,
		);

		$image = Jetpack_PostImages::get_image( $post_id, $args );

		if ( ! empty( $image ) ) {
			$image['width']  = '';
			$image['height'] = '';
			$image['crop']   = '';

			if ( array_key_exists( $size, $_wp_additional_image_sizes ) ) {
				$image['width']  = $_wp_additional_image_sizes[ $size ]['width'];
				$image['height'] = $_wp_additional_image_sizes[ $size ]['height'];
				$image['crop']   = $_wp_additional_image_sizes[ $size ]['crop'];
			}

			$image_src = Jetpack_PostImages::fit_image_url( $image['src'], $image['width'], $image['height'] );

			// Use the theme's crop setting rather than forcing to true
			$image_src = add_query_arg( 'crop', $image['crop'], $image_src );

			return esc_url( $image_src );
		}
	}

	return esc_url( $image_src );
}

/**
 * Check if post has an image attached, including a fallback.
 *
 * @param  int $post The post ID to check.
 *
 * @return bool
 */
function jetpack_has_featured_image( $post = null ) {
	return (bool) get_the_post_thumbnail( $post );
}

/**
 * Adds custom class to the array of post classes.
 *
 * @param array  $classes Classes for the post element.
 * @param array  $class   Optional. Comma separated list of additional classes.
 * @param array  $post_id Unique The post ID to check
 *
 * @return array $classes
 */
function jetpack_featured_images_post_class( $classes, $class, $post_id ) {
	$post_password_required = post_password_required( $post_id );
	$opts                   = jetpack_featured_images_get_settings();

	if ( jetpack_has_featured_image( $post_id ) && (bool) 1 === (bool) $opts['fallback-option'] && ! is_attachment() && ! $post_password_required && 'post' === get_post_type() ) {
		$classes[] = 'has-post-thumbnail';
	}

	return $classes;
}
add_filter( 'post_class', 'jetpack_featured_images_post_class', 10, 3 );